The present invention relates to a pull type fastener for a fastening system for manufacturing articles such as shipping containers and the like.
Articles such as shipping containers are frequently of a construction including a hard metal exterior layer and one or more interior layers of softer materials such as plywood, fiberboard, etc. In fastening the layers together, pull type fasteners can be used of a type generally shown in the U.S. Pat. No. 3,515,419 issued to C. W. Baugh on June 2, 1970.
The latter form of pull type fastener includes a pin and a sleeve and is set by applying a relative axial force between the pin and sleeve via a pull portion on the pin; the excess or pull portion of the shank of the pin is severed upon completion of the installation. With this type of fastener, it is desirable that the fastener component engaging the interior surface of the workpiece have a relatively large head to provide good load distribution to inhibit crushing. It is also desirable that the fastener, after being set, have a relatively low profile and a smooth surface on the interior side; in a container application this contributes to maximizing the interior load carrying volume and in avoiding snagging of the contents on fastener protrusions. It is also desirable that the set fastener inhibit tampering, i.e. unauthorized fastener removal. In some cases, it may also be desirable that the fastener have a large bearing, low profile head to engage the outer container surface.
One of the problems with fastening systems providing the above features is that the installation procedure can be time consuming and/or costly. For example with a fastener of the type shown in the Baugh patent, supra, numerous installation steps are necessary.
For example, in the fabrication of shipping containers, the body of the container is plywood, or the like with structural connections between walls being made by metal brackets, straps, etc. Frequently these metal brackets, straps, etc. have preformed mounting holes. It is a common practice for the fastener to be installed by a single operator. Here the fastener opening through the container wall or body is first drilled by the operator from the outside or metal surface side. The operator then moves into the container or opposite side to insert a large headed sleeve (such as shown in Baugh). Now the operator returns to the exterior side of the container and inserts the shank of the cooperating pin into the sleeve with the pin head on the exterior side. Finally the same operator returns to the interior side, applies an installation tool to the protruding pin shank, and actuates the tool to set the fastener. It should be noted that in the above sequence there is a possibility that the sleeve or pin can fall out before the operator has had an opportunity to complete the next step. Of course, the number of steps required of a single operator would be somewhat simplified if two operators were used, i.e. one on the inside and one on the outside of the container. In either case the procedure is costly.
With the present invention, a fastener construction is shown which facilitates installation by a single operator with a minimum of steps, i.e. the operator need move from outside to inside (or the reverse) only once to install the fastener. At the same time, the fastener of the present invention provides a unique mechanical lock to secure the pin and sleeve together. In some constructions, such as in the Baugh patent supra, a friction lock is used to hold the pin and sleeve together. Thus, with that fastener, the magnitude of the installation load and hence ultimate clamp up of the workpieces was reduced to avoid excessive pin bounce and possible separation of pin and sleeve at pin break. With the mechanical lock of the present invention, the installation loads and hence final clamp up can be increased since pin bounce and separation of pin and sleeve upon pin break are inhibited.
In one form of the invention a multiple piece fastener construction is utilized which fastener construction provides, among other features, the noted ease of installation and desirable mechanical lock.
The invention also provides means for readily accommodating workpieces varying in total thickness over a relatively wide range of thicknesses. The fastener of the present invention also provides a unique construction for retaining the pin in the workpiece openings prior to installation under a sufficiently high load to inhibit the pin from falling out or being pushed out during subsequent installation steps.
Thus it is an object of the present invention to provide a new and improved fastening system including a unique pull type fastener for securing structural assemblies of the type noted in which the fastener can be installed by a single operator with a simplified procedure.
It is another object to provide a fastener, of the above noted type, having a unique mechanical lock between pin and sleeve.
It is another object to provide a unique fastener construction in which the pin can be securely preassembled to the workpieces and held in place for the subsequent installation steps.
It is a general object of the present invention to provide new and improved fastening system including unique fastener constructions for manufacturing shipping containers or the like.